Reply by Loren

Usually the ends are plunged to full depth first and thewaste in between removed in passes about 1/4” deep.

For a wider mortise, cut a narrow one to full depth,then clamp a piece of scrap the width of the offsetyou need for the second pass to the piece youare mortising. This way you can leave the fenceset up the same. Then plunge the ends of the second half of the mortise and waste out betweenas before.

For wider mortises I often make a template and usea guide bushing, eliminating the fence. The templateapproach is almost foolproof.